The present invention relates to a rotary valve for controlling the discharge of molten metal from a metallurgical vessel, the rotary valve including a refractory rotor to be rotatable about an axis within a refractory stator having a discharge channel, wherein the rotor has a flow channel to be moved into and out of alignment with the discharge channel upon rotation of the rotor about the axis and/or upon axial movement of the rotor along the axis. The present invention also relates to a refractory rotor and to a refractory stator employable in such rotary valve.
A rotary valve disclosed in DE-PS 33 06 670 achieves molten metal discharge horizontally and has a rotor designed as a relatively long valve member having therethrough a bore with a discharge port and projecting sideways horizontally out of a vessel bottom. Thus, short pouring paths cannot be achieved, and there is a high risk of freezing of the metal. Also, since the valve member is made of a refractory material and has therethrough an axial bore, it is not possible to transfer to the rotors sufficient torque, when the rotor is tightly seated against the stator, to rotate the rotor, when the rotor and stator are subjected to thermal expansion. Further, the rotor has relatively thin walls as a result of which the rotor is susceptible to wearing out rapidly.
In a rotary valve disclosed in GB-PS 183 241, the stator and rotor are arranged substantially below the vessel bottom, so that there is a significant risk of freezing of the molten metal. Furthermore, the rotor has an axis of rotation that is perpendicular to a vertical discharge channel of the stator and flow channel extending perpendicular to such axis of rotation.
DE-PS 35 40 202 discloses a valve for controlling the discharge of molten metal to a continuous casting installation wherein the cross-section of a discharge opening can be regulated. The valve includes two concentrically and vertically arranged tubes with holes for passage therethrough of the molten metal. By adjusting at least one of the tubes, the openings of the tubes may be brought into or out of alignment. The relative motion of the tubes may be rotary and/or axial. The inner tube may be formed as a casting tube. Movement is achieved by an operation from above the melt, with the result that the movement control elements can interfere with necessary transport devices. Further, the operating elements thus are arranged in an area of very high temperature and are exposed to the molten metal itself.